Select Photo Nodes by Tags using XPath

I have been driving myself up the wall with this one.
I have a file containing information about photographs and their tags. I want to be able to find photos with certain tags or parts of tag. A section of the file is shown below.

Using an XMLDOMDocument I have tried a search patterns......SelectNodes("photodatabase/photo[contains(tag, 'Places/Great Britain/Scotland')]").
And ...SelectNodes("photodatabase/photo[starts-with(tag, 'Places/Great Britain/Scotland')]").
These return "06501.JPG" and "06502.JPG" but not "06503.JPG". The difference being that "<tag>Places/Great Britain/Scotland/Cardoness</tag>" is not the first node.

This doesn't apply to..."...SelectNodes(photodatabase/photo[tag='Places/Great Britain/Scotland/Cardoness'])".The problem is that the complete path will not always be specified as the user may sometimes

want any photos in Scotland.
I have the feeling that an "axis" is the answer.